https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68600
--- Comment #10 from Dominique d'Humieres <dominiq at lps dot ens.fr> --- > I think you are seeing the effects of inefficiencies of assumed-shape arrays. > > If you want to use matmul on very small matrix sizes, it is best to > use fixed-size explicit arrays. Then IMO the matmul inlining should be restricted to fixed-size explicit arrays. Could this be done before the release of gcc-6?